Stone finishing machine



g. 17, 1937. F. PIERCE STONE FINISHING MACHINE Filed Feb. 1o, 1956 5 sheets-'sheet 1 Cil. wenn..

Aug. 17, 1937. Fr PIERCE STONE FINISHING MACHINE s lsheets-sheet 2 Filed Feb. 1o, 195e Hfsein.

Aug. 17, 1937. F. PIERCE sToNE FINISHING MACHINE 5 Sheets-Sheet 5 Filvled Feb. l0, 1956 5 e. .IDI 2 wm a 4 5 l mm" I hui. :I v 1 w/ i w W w f a lm l/ F.0d H Z W f 4 w a M .ih uj l l I.. Q -LT rHiiJ/ m i l |5 N .w I

L m V 7 IIL. .L -------IlllL J rt 5 T J C L. l w f 6 M S 2 0 l J Patented Aug. 17, 1937 UNITED STATES PATENT OFFICE 7 Claims.

This invention relates to a machine for producing a plane or formed surface on a block of granite or other stone.

It is the general object of my invention to provide an improved machine for such purposes by which a plane or formed surface of any desired contour may be easily and economically produced.

In the preferred embodiment of my invention, I provide a grinding drum movable vertically during the grinding operation and I also provide means for moving said grinding drum or the work relatively horizontally in accordance with a desired pattern. I also provide means by which the horizontal movement may be automatically controlled.

My invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of the invention is shown in the drawings, in which Fig. 1 is a side elevation of my improved machine; Fig. 2 is a plan view thereof;

Fig. 3 is a rear elevation thereof; Fig, 4 is a detail plan view, looking in the direction of the arrow 4 in Fig. 3;

Figs. 5 and 6 are enlarged side elevations of ,30 certain parts;

Fig. 7 is a detail plan view to be described, and Figs. 8 and 9 are front and end views of a grinding drum.

Referring to the drawings, my improved stone finishing machine preferably comprises a base l0 (Fig. 1) on which a work supporting table Il is slidably mounted. The table Il may be moved toward and away from a grinding drum l2 by a feed screw I3 (Fig. 2) connected by bevel gears vI4 and l5 to a back shaft I6 which in turnymay be connected by a gear Il and a pinion i8 to a shaft l 9, which is rotated through a speed-reducing device 20 from the armature shaft 2l of a reversible motor M.

The back shaft I6 may also be directly connected by a gear 22 and pinion 23 to the armature shaft 2l to provide a high speed drive for moving the work to or away from operative position. Suitable provision is made for selectively 50 connecting the ,gears I1 and 22 to the back shaft I6.

The table Il is preferably provided with an upstanding back portion 25 (Fig. 2) and with an end portion 26 (Fig. l) movable to accommodate 55 longer or shorter stones, both portions 25 and 26 being formed integral with or rigidly secured to the table Il. A block of stone Si is placed on the table l I, preferably resting on wood strips 21 (Fig. 1) and is so located as to be positioned by the back 25 and end portion 26. 5

A clamping arm 30 (Fig. 2) is pivoted at 3l on the end portion 26 and is provided with a clamping screw 32 at its outer end. The arm 30 is also provided with a lug or flange 33 normally engaginga block 34 (Fig. 4) at the end of a 10 spring plunger 35. When the block 34 is in normal position, the arm 30 is held from angular movement and pressure may be applied to the stone S b-y means of the clamping screw 32 and hand wheel 36. By such application of pressure, 15 the stone S is forced against the back 25 or against interposed wood strips 3l (Fig. 2).

When a stone is to be removed and replaced it is desirable that the arm 30 be swung out of operative position. For this purpose I provide a 20 hand lever 40 (Fig. 4) engaging a collar 4l on the spring plunger 35. By moving the hand lever in the direction of the arrow a` in Fig. 4, the block 34 may be removed from holding position so that the arm 30 is free to swing away from the 25 stone Si.

When the arm 30 is returned to operative position, the block 34 automatically resumes its normal holding position.

The grinding drum l2 (Fig. 2) previously men- 30 tioned, is mounted on one end of a grinding shaft which is an extension of or coupled to the rotating element of the grinding motor M'. 'Ihese several parts are supported by a grinding carriage 46 (Fig. 3) which is vertically slidable 35 on guideways on a xed stand or post 41 (Fig. l)

The grinding carriage 46 is raised or lowered by a feed screw 50 (Fig. 3) having a worm gear 5| at its upper end, engaged by a worm 52 mounted on the armature shaft of a reversible motor M2 secured at the top of the post 4l. The post 4l is preferably of hollow construction and constitutes a casing for a heavy counterweight 53, suspended by a cable 54 which runs over a sheave 55 and has its other end connected to the grinding 45 carriage 46.

By rotating the motor M2 in one direction or the other, the carriage 46, together with the grinding drum I2 and grinding motor M', may be fed up-ward or downward as desired. The coun- 50 terweight 53 substantially reduces the load on the motor.

The grinding action in my improved machine is effected by gravity feed of a continuous supply of steel shot or other similar abrasive to the 55 converging space between the upper surface of the grinding drum I2 and the upright end face of the stone. The drum I2 is commonly formed of cast iron or soft steel and may be of either one-piece or disc construction and with either a straight or formed face.

As it is desirable to use the steel shot over and over, I preferably provide a conveying mechanism to return the shot to feeding position. This mechanism comprises a belt 60 (Fig. 1) having a plurality of buckets 6| and running on a lower conveyor pulley 62 and an upper pulley 53. At its lower end, the conveyor extends into a well or pocket 54 in which the steel shot collects after passing the grinding drum.

The bucket conveyor is enclosed by a casing 65 (Fig. l) and at its upper end is provided with an offset portion 99 having aV delivery l pipe 61 through which the shot raised by thelbuckets is delivered to a feed chute 68 which extends to the upper edge of the stone surfaceto be finished.

The grinding drumy I2 (Fig. 5) is provided with a wheel guard or casing 'III which at its upper end supports a plate 'II which is engaged by the shot fed from the trough 61 during the grinding operation, and which deflects the shot so that they fall by gravity into the converging space between the upper portion of the drum I2 and the adjacent face of theY stone S.

Any suitable provision may be made for driving the conveyor belt 60. In Fig. 1, I have indicated the lower pulley 62 as provided with a worm wheel l2 engaged by a worm 'I3 connected by bevel I gears 'i4 and 'I5 to the armature shaft I6 of a Y shaft 45 and grinding motor M may be mounted in a bearing structure 32, formed separate from the carriage 46 and'slidable endwise in the guideways 89. y

A worm 83 (Fig. 7) is rotatably mounted in the bearing structure 8,2 and is held from axial movement relative to said structure. The worm-83 may be driven from the grinding shaft 45 through any usual gear connection, as 84-84 (Fig. 7). The worm 83 engages a worm wheel 85 mounted to rotate about a bearing stud 8B on the structure 82 and having associated therewith an eccentric 8T rotatable in a circular opening in one end of an eccentric link S8. The opposite end of the link 88 is pivoted on a stud 89 mounted in a bracket 98 carried by the grinding carriage 46.

As the grinding wheel shaft rotates, the worm shaft 85, and eccentric 81 are also rotated, and as one end of the link 88 is fixed, the rotation of these parts causes a relatively slow axial oscillation of the bearing structure 82 and its associated parts, as indicated by the double arrow b in Fig. 7.

I will now describe the mechanism by which the stone S may be fed automatically ,toward or away from the grinding drum I2 to produce a desired contour. For this purpose I provide a flexible templet or pattern 92 (Figs. 1 and' 5) having a plurality of slotted bars 93 pivotally connected thereto.

At the rear of the back portion 25 I provide a vertical flange 94 (Fig. 2) having a T-slot 95 to receive bolts 96 which also extend through the slots in the bars 93. By bending the flexible templet 92 and securing the bars 93 in selected The arm (Fig. 6) has a circuit-closing extension I I0, the outer end of which is positioned between upper and lower contact screws III and ||2. A spring |I3 tends to press the roll |00 againstthe templet 92.

The Contact screws III and |I2 are connected by wires I I4 to any usual control mechanism by which the motor M may be caused to rotate in selected directions. Y

The operation of my automatic control mechanism is as followsz-When the parts are in the position shown in Fig. 1, the bracket |93 is adjusted by the hand wheel |95 so that the extension III) will be in neutral position vand. out of engagement with either contact screw I| or ||2. As the grinding drum is moved downward, the roll may presently engage a portion of the templet 92 curving to the left in Fig. 1. Such engagement will swing the arm |il| Von its pivot |02 and will cause the extension I I0 to engage the contact screw |I2. to rotate in a direction to withdraw the stone S from the grinding drum IZ'until the contact arm IUI is again in neutral position. Y

If on the other hand the templet 92`recedes from the roll |89, the spring IIS swings the arm I0 against the contact screw I| and the motor i M is rotated to advancey the stone toward the grinding drum. In this way the stone is withdrawn or advanced in accordance with the indications of the templet 92, and the configuration of the templet is reproduced in the finished surface of the stone.

It will be understood that suitable switches and connections are provided for starting .and stopping the motors M and M3 and for causing the motors M and M2 to rotate in selected directions. Provision is also made for supplying water to the grinding drum.

While my improved finishing machine gives excellent satisfaction when providedrwithV a plain surface drum, the cutting rate may be increased under some circumstances by providing serrations |I (Fig. 9) in the face of a drum ||6, said serrations preferably) having inclined or oblique following surfaces as shown in Fig. 9.

Having thus described my invention and the operation thereof, it will be seen that I have provided a simple and efficient machine for automatically producing a contoured surface on a piece of granite or other stone. The grinding drum has a straight line vertical feeding movement on the iixed post 41, and the stone S has sufficient horizontal movement to advance the stone to grinding position and to duplicate the contours of the pattern.

The Work of removing stock from the stone is very rapidly and effectively performed by the steel shot, fed by gravity into the converging recess between the drum and the stone, and the grinding drum may be iiooded with shot, as the surplus shot is all promptly returned by the bucket con- This will cause the motor MV a contoured surface may be produced on a block of granite or other stone more rapidly and much more economically than by any other grinding machine or stone finishing machine with which I am familiar.

Having thus described my invention and the advantages thereof, I do not wish to be limited' to the details herein disclosed, otherwise than as set forth in the claims, but what I claim istl. A stone finishing machine comprising means to support a stone, a grinding drum, means to support said drum for rotation on a horizontal axis, means to move said drum vertically downward in the direction of a grinding cut, said drum engaging said stone at one side of said drum and substantially at the horizontal level of its axis, means to feed loose abrasive into the converging recess between the upper surface of said drum and the stone, and means to rotate said drum so that the surface thereof adjacent said stone moves downward at its point of engagement therewith.

2. A? stone finishing machine comprising a grinding drum rotatable about a horizontal axis, means to feed said drum vertically in the direction of a grinding cut, a stone supporting table, pattern-controlled automatic means to cause said table to horizontally approach or recede from said drum during said vertical grinding operation, means to rotate said drum so that the surface thereof adjacent said stone. moves downward, and means to feed loose abrasive to said stone above said grinding drum.

3. A stone finishing machine having, in combination, a work supporting table, means to move said table horizontally, a grinding drum, means to feed said drum vertically in the direction of a grinding cut, a pattern associated with said machine, and automatic means controlled by said pattern and effective to advance or withdraw said stone horizontally relative to said drum as said drum is fed vertically downward.

4. A stone finishing machine having, in combination, a work supporting table, means to move said table horizontally, a grinding drum, means to feed said drum vertically in the direction of a grinding cut, means to present loose abrasive for gravity feed to said drum, a pattern mounted in said machine, and automatic means controlled by said pattern effective to cause said drum and stone to horizontally approach or recede with respect to each other as said drum is fed vertically downward.

5. In ,a stone finishing machine, a grinding drum, means to feed said drum vertically in the direction of the grinding cut, a work supporting table., a reversible motor to move said table horizontally toward or away from said grinding drum, a pattern bar mounted on said table, a roll engaging said bar, a supporting arm for said roll mounted for vertical movement with said drum, and contact devices at both sides of said arm and movable vertically therewith, said devices being selectively engageable by said arm when said roll is displaced from normal angular position by said bar during relative vertical movement between said roll and bar, and said contacts controlling said reversing motor.

6. In a stone finishing machine, a fixed pattern support, a flexible pattern member, .and means to secure said pattern member to said fixed support at a plurality of spaced points and in a selected configuration, said latter means comprising a plurality of slotted bars pivotally connected at spaced points to said flexible pattern member, and securing devices mounted in said fixed support and extending through the slots in said bars.

7. A stone finishing machine having, in combination, a work supporting table, means to move said table horizontally, a grinding drum, means to feed said drum vertically, means to feed loose vabrasive to said drum, a motor for said grinding drum, a bearing structure for said grinding drum and motor, a grinding carriage on which said bearing structure is horizontally slidable, an eccentric, means to drive said eccentric, a link having an opening at one end for said eccentric, and a stud on said carriage on which the other end of said link is pivoted.

FRANK PIERCE. 

